#include <iostream>
using namespace std;

int main()
{
	double x;
	scanf("%lf",&x);
	
	double l = -10000,r = 10000;
	while(r - l > 1e-8)
	{
		double mid = (l + r)/ 2;
		if(mid*mid*mid>=x) r = mid;
		else l = mid;
	}
	printf("%lf",l);
	return 0;
}
